The present invention relates generally to a system for attenuating sound transmission between a sound source and a destination and specifically to a sound barrier system capable of economical mass manufacture to lessen the impact of the noise caused by vehicular traffic or construction in nearby areas.
In a growing number of transportation related settings, federal, state and local governments are specifying, supplying and installing sound barriers between roadways and the surrounding areas, particularly in areas of high traffic volume. Sound barriers are desirable in residential and commercial areas proximate interstate highways to attenuate noise in neighborhoods, shopping districts, and other commercial areas caused by traffic.
Various materials are presently employed in the design and manufacture of various sound barriers. Prior art barrier designs constructed of steel, concrete, cement board, wood, and earthen barriers have been employed to effect a reduction of ambient noise levels proximate noisy roadways or construction sites. However, each have various disadvantages that make widespread production and installation impractical, either due to cost, manufacture and installation complexity, or poor sound attenuation.
Steel and metal barriers are prone to denting and chipping, as well as corrosion, and are extremely heavy. Wood barriers require periodic maintenance and have a comparatively short useful life. Concrete and cement barriers are very expensive to produce and install. Earthen barriers require a great deal of space to erect and are subject to erosion over time. Furthermore, each of these barrier designs requires labor intensive installation techniques, thereby placing a premium on product life. Additionally, none of the aforementioned barrier designs are particularly aesthetically pleasing, and all are susceptible to the application of graffiti and the like.
Additionally, the installation of many prior art sound barriers requires an excess of installation hardware and complex mechanical hardware for assembling the barrier panels. Concrete and steel barriers require heavy equipment to place the barriers, and robust structural supports to hold the barriers in place due to their weight. Furthermore, the labor required to construct these barrier systems is quite costly.
Since sound barriers are often used to protect residential areas, hospitals, schools, and housing developments from high noise areas like roadways, construction sites, and shopping centers, the design and construction of economical and easily installed barriers is of particular import to quality of life in the modern world.
The present invention solves the aforementioned problems by providing an economical sound barrier that is capable of production by modern mass manufacturing techniques and easily installed in a plurality of noise reduction applications. The sound barrier system of the instant invention utilizes a plurality of barrier panels constructed of aluminum skin panels. The aluminum panels may be of varying gauges and have varying gaps and filler materials therebetween, depending upon application requirements. Furthermore, the barrier panels are readily installed by mounting on extruded or welded poles of steel or aluminum with a minimum of hardware. The barrier panel design of the present invention provides for modular panels that are vertically interlocking to achieve a sound barrier system of a desired height without the need to construct panels that are both wide and tall.
In a typical barrier installation, sound transmitted from a source (e.g., vehicular traffic) reaches a receiver by two paths. The first path, shown in FIG. 1 is the distance (C+D) is a path taken by sound transmitted through the barrier. The second path, shown as the distance (A+B) is a path taken by sound passing over the barrier.
The sound passing through the barrier should be minimized in order to maximize the effectiveness of a barrier for a given application. The barrier construction must be such that the sound transmitted via the path C+D is much less than the sound diffracted over the barrier via path A+B. The sound passing over the barrier via path A+B depends on a plurality of factors that vary with each installation including but not limited to barrier height and length, source and receiver height, ground contour and impedance, wind direction and velocity, and temperature gradients.
If a given barrier meets a minimum standard of sound attenuation, as described in further detail hereinbelow, the sound passing over the barrier is independent of the barrier material and construction. Any sound transmitted via the path C+D depends upon the barrier material, design, and construction details. It is independent of the installation-specific factors mentioned above.
The minimum standard for barrier attenuation is determined by assuming an ideal barrier (one in which no sound is transmitted via path C+D), wherein the only sound reaching the receiver is via path A+B. As one example, consider an application wherein a barrier having height of 12 feet is employed, wherein the distances A=B=100 feet are assumed so that the barrier is disposed equidistant from the source and the receiver. For purposes of this analysis it is given that the barrier is very long such that transmitted sound does not reach the receiver by passing around the ends of the barrier. Furthermore, wind and temperature gradients are negligible, and the ground is flat with no ground effect.
FIG. 2 is a graph of the sound pressure level in decibels (dB) at the receiver with and without an ideal noise barrier present. FIG. 2 further shows the insertion loss of the barrier for this example. The insertion loss is simply the difference between the sound pressure level at the receiver with and without the barrier in place. In order for a given barrier in FIG. 2 to meet the minimum required standard of sound attenuation, the transmission loss of the barrier (the attenuation of sound through the barrier via path C+D) must be much greater than the barrier""s insertion loss; 10 dB is typically required in the industry. The transmission loss of a barrier using the 10 dB criterion is also plotted in FIG. 2.
The aluminum barrier panels provided by the present invention provide the requisite reduction in sound transmission while being extremely lightweight and easily installed. Furthermore, the barrier panels of the present invention are amenable to embossing and to the application of coatings and colors with a wide variety of patterns by modern manufacturing technique, at relatively low cost. This feature of the invention allows for an economical sound barrier that is aesthetically pleasing as well as resistant to graffiti.
It is therefore one object of the instant invention to provide an improved sound attenuation barrier device for use near high-noise areas.
A further object of the invention is a lightweight sound barrier system.
A further object of the invention is an easily manufactured sound barrier that is low in cost.
A further object of the invention is a sound barrier that is installed with a minimum of labor and hardware cost.
A further object of the invention is a sound barrier having a plurality of embossed textures and color coatings, for improved aesthetic appearance.
Other uses, advantages, and features of the instant invention will become apparent after reading the detailed description of the preferred embodiments taken in conjunction with the accompanying drawing figures.